Method of treating veneers



Patented 0.1.24, 1939 UNlTED STATES *PATENT'O'FFICE 7 2,171,160 METHODor" 'ram'rma VENEERS Frank V. Tischer, Dayton, Ohio; Anna M. Tischer,executrl'x of said Frank -V. 'lischer, deceased, assignor to Anna M.Tlscher No Drawing.

ing veneers and to a composition for use in practicing that method.

When a veneer is subjected to moisture it swells ,l droscopic matterwhich serves to unite the fibers into an integral structure. When a logis cut into veneers it must be cut in sections across the fibers of thewood to produce the desired configuration or figure in the veneer and asa result in many cases the veneer'contains both straight or longitudinalgrain" and end or cross grain. In the ordinary process of veneeringliquid glue is applied to the veneer and the latter is then applied tothe core or body of the panel or other structure to which it is to beattached and the panel subjected to pressure in a press. The"application of moisture to the veneer causes the straight grains toswell, thus increasing the thickness ofthe straight grain portions ofthe veneer while the end grain portions do not increase appreciably inthickness and this inequality cannot be corrected by the pressure towhich the panel is subjected. Asa result of this inequality in thicknessof the different portions of the veneer air pockets are formed whichprevent the proper adherence of the veneer to the core and result in theformation of blisters in the finished product. One object of theinvention is to provide a method of treating veneers to prevent theformation of blisters in the finished product. I

A further object of the invention is to provide a method'of so treatinga veneer that the straight grain and end grain will be maintained atequal when'subjected tomoisture.

A further object or the invention is to provide a method of treating aveneer to render the mat:

' fibers to render the same non-hydroscopic, then dry the veneer andsubject the same to pressure and heat to cause the composition topenetrate thickness and th"stra ight.grain will not swell' ApplicationNovember 23, 1933, Serial-N0. 112,308

3 Claims. (01. 21+23) This invention relates to a method of treat theveneer and to eliminate any inequality in the thickness of the straightgrain and end grain.

The composition with which the veneeris.

. treated comprises a suitable acid oxidizing agent which is dissolvedin water and then reduced by 5 a suitable alkali until it is neutral tolitmus paper. A solutionof about Baum in strength gives satisfactoryresults but, of course, the strength may vary.

Preferably in the preparation of the composi- 10 tion I dissolve twopounds of animal hide glue in one gallon of water, bythe addition ofheat, and

add. to the solution while hot one pint of a neutralized oxidizing agentin solution. The compo- I sition thus formed is then spread on theveneer,

' preferably on both sides thereof, and the coated veneer is thenallowed to dry. The time required forproper drying ,varies, according tothe character of the veneer, from one totwelve hours in a roomtemperature of 65 to 70 F. and about 40 to -50 relative humidity. Thedry coated veneer is then placed between hot plates and subjected topressure. Preferably the plates are steam heated and have about thirtyto forty pounds steam pressure and about'one hundred pounds per squareinch weight pressure, andwith such plates the pressure isrcontinued fora period varying from one to five minutes, according to the requirementsof the veneer. The action of the heat and r pressure on the neutraloxidizing agent and the acid moisture of the veneer causes thecomposition to penetrate the veneer and to oxidize the glue and thehydroscopic matter between the wood fibers, thus rendering the latternonhygroscopic. The pressure. plates tend to equalize the thickness ofall parts of the veneer and the lat-. ter, when removed from the press,is fiat and of equal thickness in the straight grain and in. the endgrain thereof. The glue in the composition 1 is not deteriorated by theaction of the heat and 40 the composition provides the veneer with asurvface to which glue, subsequently applied thereto,

will readily adhere. "The pressure plates are preferably of iron as thecoated veneers will not adhere to iron plates but may be readily removedtherefrom. I

When a veneer which has been so treated is subsequently attached tothecore or body of the panel by the, application of liquid glue theretothe straight-grain will not swell, due, I believe, to the fact that thematter between the wood fibers has 5 been oxidized and thus lost itsability to absorb moisture. As a .result the panel, of which the veneerforms a part, is entirely free from blisters. Any suitable oxidizingagent and alkali may be employed in the forming of the composition but Iprefer to use bichromate of potash or bichromate of soda as an oxidizingagent and to neutralize the same by the addition of sodium carbonate andsodium chloride. The three ingredients are employed in approximatelyequal quantities, say about one-half pound of each to a gallon of water.I prefer these ingredients because they are easy to combine, inexpensiveand the solution so formed is stable throughout the year and, further,the dried coating formed by this composition adheres readily to gluesubsequently applied. However, other ingredients may be used, such asnitric acid as an oxidizing agent and aluminum hydrox-id or lead}hydroxid as the,

neutralizing agent.

While the use of glue in the composition is desirable it is notessential to the oxidation of the hy roscopic matter and this may beaccomplished without the use of glue.

While I have described the preferred method of practicing my inventionand the preferred composition for use therein I wish it to be understoodthatI do not desire to be limited to the details thereof as variousmodifications may occur to one skilled in the art. c

Having now fully described my invention, what I claim as new and desireto secure by Letters Patent, is:

1. A method-of treating a veneer prior to gluing to render thehydroscopic matter therein nonhydroscopic, which comprises coating bothsides of the veneer with a composition including a neutralized oxidizingagent and glue, drying the coated veneer and subjecting the dried coatedveneer individually to pressure in the presence of heat to cause saidoxidizing agent to penetrate the veneer and act on the hydroscopicmatter therein.

2. A method of treating a veneer prior to gluing to render thehydroscopic matter therein nonhydroscopic, which comprises coating bothsides of the veneer with a composition including a neutralized oxidizingagent and glue, drying the coated veneer and subjecting the dried coatedveneer individually to pressure between hot metal plates to cause saidoxidizing agent to penetrate the veneer and act on the hydroscopicmatter therein and to flatten the surfaces of said veneer.

3. A method of treating a veneer prior to gluing to render thehydroscopic mattertherein nonhydroscopic, which comprises coating bothsides of a veneer with a solution including an acid oxidizing agent, analkali and glue, drying the coated veneer and subjecting the driedcoated veneer individually to pressure between hot metal plates.

FRANK V.

